Reciprocatory piston engines



Oct. 31, 1961 E. L. SHAW RECIPROCATORY PISTON ENGINES 2 Sheets-Sheet 1 Filed 001;. 6, 1960 1 INVENTOR. EDWIN L. SHAW wafi HR 5..

m I 1! IX l @m i wm Z N \N 5 6 l @h V B Q vfi Ev wmixvmw mw\ mm 5 fiillw m Y \w Oct. 31, 1961 E. L. SHAW 3,006,324

RECIPROCATORY PISTON ENGINES Filed Oct. 6, 1960 2 Sheets-Sheet 2 A l COMPRESSION POWER j 8 12000 STROKE STROKE g IOOOO COMBINED LOADS o 000.- GAS LOADS 6000 Z 4000 B (I) 2000 g 0 50 TDC 9 2000 I80 4 360 8000 pss'ron INERTIA 0000 LOADS SHAFT ANGLE IN DEGREES JNVENTOR.

Eowm L. SHAW United States Patent Ofihce 3,006,324 Patented Oct. 31, 1961 3,006,324 RECIPROCATORY PISTON ENGINES Edwin L. Shaw, Oxnard, Calif., assignor to American Brake Shoe Company, New York, N.Y., a corporation of Delaware Filed Oct. 6, 1960, Ser. No. 60,837 9 Claims. (Cl. 121-119) This invention relates to bar-rel engines and more particularly to new and improved structure for balancing gas loads and inertia loads applied to piston shoes that are utilized to transmit power between the pistons and the swash plate of a barrel engine.

A barrel engine, in general, is an engine comprising one or more pistons that are driven reciprocably along paths parallel to the axis of a rotatable member such as an engine shaft. In one kind of barrel engine a swash plate is provided, having at least one .inclined surface which is usually disposed at a fixed angle with respect to the rotational axis of the swash plate. The rotational axis of the swash plate is parallel to the direction of reciprocation of the piston. Rotary motion of the swash plate, as well as a power take-oil shaft, which is oftentimes fixed for rotation with the swash plate, is achieved by the camming action afforded by the piston shoes on the inclined surface of the swash plate. Thus, the gas expansion force which produces a power stroke of the piston is transmitted directly through the piston shoe to the swash plate. Also, the reciprocatory motion of the piston develops a substantial inertia force on the piston shoe, particularly at the end of the piston stroke wherein the direction of reciprocation of the piston must be reversed. Thus, each piston shoe is periodically moved toward engagement with the inclined surface of the swash plate by forces of considerable magnitude in the course of operation of the barrel engine. A barrel engine of this type is shown in patent No. 1,694,938 to Harris.

It is a primary object of the present invention to balance both the gas and inertia forces or loads exerted on the piston shoe by developing a pad of pressurized fluid between the adjacent surfaces of each piston shoe and the swash plate.

In accordance with the present invention a construction which enables the aforesaid balancing action to be obtained preferably includes a balancing piston which is carried within the main or power piston and which defines a fluid-pressurizing chamber located within the main or power piston. Thus, the main or power piston is formed with an inner bore which extends axially therein. A balance piston is disposed with one end portion slidably mounted within the bore to define a variable-volume fluidpressurizing chamber in the bore. A conduit is provided for conveying fluid to the chamber and a check valve is utilized to prevent reverse flow of fluid from the chamber back through the conduit. With this construction, movement of the balance piston inwardly of the bore during reciprocation of the main or power piston is effective to apply pressure to the fluid within the lluid-pressurizing chamber. An additional conduit is provided to conduct the fluid, under pressure, from the chamber through the piston shoe and between the adjacent surfaces of the piston shoe and swash plate. It is a further object of the present invention to incorporate the foregoing structural features in a novel barrel engine construction.

It is a related object to utilize a number of fluid-pressurizing chambers as aforesaid, in a barrel engine having a plurality of main or power pistons, to provide hydraulic pressure on the particular piston shoe experiencing a load, at any given time, that is proportional to the load and is generated by the load itself.

It is another object of the present invention to utilize the high pressure fluid developed by the above-noted construction to lubricate the sockets or swivel mountings affording connections between the piston shoes and the main or power pistons and to lubricate the swash plate where it is engaged by the shoes.

ln some engines, the main or power piston is extended to both sides of the swash plate to serve a dual function. Thus, and as illustrtaed in Patent No. 2,083,730 to Mitchell, one end of the main piston may serve as a precompressor for applying pressure to air or other fluid in a chamber separate from the usual power chamber in which the opposite end of the piston is reciprocated. It will be recognized that a piston construction of this nature adds to the overall weight of the piston and consequently increases the inertia of the piston. Therefore, with a piston construction of this kind it is even more desirable to provide some sort of arrangement for balancing out the forces transmitted to the piston shoes by the inertia of the piston. It is therefore another object of the present invention to incorporate a balancing piston construction as aforesaid in the part of the piston extending in each direction from the swash plate to enable a balancing action to be achieved in either direction of reciprocation of the main or power piston.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention.

In the drawings:

FIG. 1 is a side elevation view, in section, of a barrel engine comprising a balancing system constructed in accordance with one embodiment of the present invention;

FIG. 2 is a fragmentary view, in section, and illustrates a balancing arrangement constructed in accordance with another embodiment of the present invention; and

FIG. 3 is a diagram graphically illustrating the relationship of the gas and inertia loads exerted on a piston shoe during one cycle of reciprocation of an individual main or power piston.

In FIG. 1 a barrel engine constructed in accordance with the present invent-ion is indicated generally by the reference numeral 11. The engine 11 comprises a combined casing and cylinder block which may be of twopart construction as indicated by the reference numerals 12A and 12B. The cylinder block 12A is formed with a number of cylinder bores 13 which are disposed parallel to one another and annularly arrayed about the longitudinal axis XX of the barrel engine 11. The cylinder block 12B is in turn formed with a plurality of cylinder bores 14, each aligned with a respective cylinder bore 13. A cylinder head 16 is connected to the cylinder block 12A by a plurality of studs 17 and nuts 18. Preferably, the cylinder head 16 is formed with dome-shaped recessed surfaces 19 in the areas aligned with the cylinder bores 13.

An end cover 21 and valve plate 22 are attached to the cylinder block 123 by suitable means such as a number of studs 23 and nuts 24. The end cover 21 is formed with an inner chamber 26 which afiords an inlet manifold communicating with the cylinder bores 14 through ports 27 formed in the valve plate 22. A flexible flapperlongitudinally extending tie bolts 29 and nuts 31.

The cylinder block 12A is formed with a circular recess 32 in the part adjacent the cylinder block 12B, and a swash plate 33 is disposed for rotation therein. The swash plate 33 is secured to a flange 34 of a shaft 36 for rotation therewith by a number of cap screws 37. The shaft 36 is in turn journalled for rotation within suitable bearings 38 and 39 mounted, respectively, within the cylinder block 12A and the end cover 21; Thus, the axis of rotation of the swash plate 33 coincides with the longitudinal axis XX of the barrel engine 11 and is disposed parallel to the cylinder bores 13 and 14. The shaft 36 may be utilized as a power take-off shaft, as described hereinafter. I 7 I A plurality of pistons 41 are incorporated in the engine 11 each piston 41 is mounted for'reciprocatory movement within an aligned pair of the cylinder bores 13 and 14, Thus, each piston'41 includes an end 41A which, with the dome-shaped recess 19, defines an expansible chamber 42 in the bore 13. The chamber 42 is adapted to serve as a power chamber in which combustion products or hot gases react on the exposed surface of the end 41A of the piston to effect a power stroke of the piston. An outlet port 43 is provided in a side wall of each bore 13 for exhausting the spent gases or combustion products from the chamber 42. A suitable inlet port, not illustrated, is also provided in the side wall of each bore 13 for supplying either a carbureted fuel-air mixture or hot gases to the chamber .42, The barrel engine 11 is preferably a two-stroke cycle engine in which each stroke of the lowermost piston 41, from the top dead-center position illustrated in FIG. 1, is a power stroke.

A piston shoe 44 of a generally hemispherical and hollow oonstruction as illustrated in fIG. 'l is interposed betwo rl tho s ash Plat 3 an tho o d A o sash P The piston shoe'44 is slidable on the swash plate and sorvss to t an mi tho li i o s hru a r d by the power stroke of the piston to the swash plate 33 to convert the linear movement of the piston into rotary movem nt r the swash pl t and sh o t s a X. 1 a wel -k own .m nnor- Each p st n 41 also in e s sa 1 wh h v l ahly isri sd fo r ip o at ry mo ion Wthih o t Thos, the nd B of tho piston, in oom'hnc toh h ho va e plate .22, dsfiho a a a'h o oloot oh hro 46 hich is util zed o P oo rnpr ssih air o th gases suppl d to ho power hambe 4 oita o ond i a d valve strh tu o ma ho i corpor t d n oony r hs manner in the barrel engine 11 for this purpose and are not. llu tra d in F G- A pist shoe 4 i n po betwee he e d 4 1 of o oh piston and tho s ash P o s 3. in the sam mann as th Pis sh ss .4 a oispo oo on the opposite surface Of h swash Pla 33: '7

As thus fo d s r b d, e struct re an operati o the barrel engine 11 are generally conventional. Thus, each of the piston shoes 44 and 47 is slidable on and trav rs s a cu r p h on ne s fa e o th s a h p te 33. Each piston shoe is periodically subjected to loads o ons derable m i ud n ho o hrso o opera on of the arre en ne,- us, on a Po r s r e o a P on 1 h ntir .fo 'ce available r m tho sxpa sioh of h s s in the chamber 42 is transmitted through the related piston shoo 44 to elop the re t n ot on ot t e a h P ots 3 d a l h p ston 1 c mp os a ma s o i nificant magnitude which builds 'up an inertia force dur in mo m nt of the p on n one n ar dir ction a whieh opposes any force tending to reverse the direction of movement of the piston. Thus, the velocity of the lowermost piston 41 illustrated in FIG. 1 progressively increases during movement of the piston, in thefirst half f th pow r s e, f om h op dead-c nte Po t on illustrated. Subsequently, as the velocity of the piston is progressively diminished during the remaining half of the power stroke, the inertia force developed by the deceleration of the piston 41 builds up progressively and is transmitted as an inertia load through the piston shoe The inertia load of the lowermost piston 41 achieves its greatest value at the bottom dead-center position of the piston when the greatest acceleration of the piston is obtained in the course of reversing the direction of movement of the piston. It will therefore be apparent that each piston shoe 44 is periodically pressed toward frictional engagement with the inclined surface of the swash plate 33 with ooosid rshl orc y b th t gas oa i ho or loads of the piston 41 during operation of the barrel engine 11. The piston shoes 47 are likewise pressed toward frictional engagement with the swash plate 33 by both the gas load and the inertia load of the associated piston 41. However, the gas loads result from the precompression of the gases in the chambers 46 rather than from the expansion of hot gases or combustion products as in the gas loads produced in the chambers 42.

In FIG. 3, the variations in the loads with the angular rotation of the swash plate 33, and thus the reciprocatory movement of the piston are illustrated for onecomplete cycle of a piston 41. In FIG. 3 it is assumed that the piston 41 weighs approximately 10 pounds; the ordinates represent the shoe loads in pounds while abscissas represent the shaft angle in degrees. Three separate load curves are plotted in FIG. 3 to indicate the gas loads, piston inertia loads, and combined loads as indicated by the respective legends. It should be noted that the curves illustrated in FIG. 3 represent only approximate values and serve primarily to indicate the general relationship of the shoe loads to the operational cycle of a piston and h e a an eme The curves illustrated in FIG. 3 may be correlated it tho o i ins str othro ho n to 1 y considering the uppermost piston illustrated in FIG. 1 in which th Powor fon o o pts oh a h b tt m. dead-center po ition and is indi ate by tho rst soo ohsrastsr A- Th is th P si n whsr ih h ine t tor h o the Pi o e r s it r s s t o on ho a so a e P oo shoe 44 inasmuch as the direction of linear movement of the piston must be completely reversed, and the acceleration of the pisto s ns quen y at ts ea e t a oo- R orring'now to FIG. 3, this position of the piston corresp nd to ho Po nt indi ed b h o o ooo hs sot A i .FIG. 3, a d the loa x r d n the pist sho is approximately 1200 pounds. As the piston 6nd 412; is moved from the bottom dead-center position illustrated in 1 toward its top dead-center position, the inertia load on the piston shoe progressively decreases and passes t ou h ro a a shaft p o mo n l o p ro thstoly .90 dogr o as i d sto by t o rsfsrshoo s to B in FIG- '1 Th sorr so s pp x m y to the mid-portion of the compression stroke of the piston end 41A wherein the velocity of the piston is at its greatest raho- Du i this al o he retu or pr s i strok of the end o the P o very little sotnp sion of the gases within the chamber 42 is achieved, so that th as lo d on ho P s on shoe 44 r of nos hl ma nitu e As tho en A o o t move wa the top dead-center position the polarity of the inertia load exerted on th Piston h s 4 pass r p tive to a negative value but progressiyely builds up in magnitude. Thus, the inertia of the piston directly opposes the gas load at the top deadtcenter position of the end 41A of the piston so that the combined load is the numerical difference between the gas and inertia loads. In the barrel engine construction illustrated in FIG. 1 the inertia loads are larger in magnitude than the gas loads so that at the top dead-center position the combined load is a negative value, and the piston shoe 44 is not pressed toward engagement with the swash plate 33. This relationship holds t e fo h reater po tion of t first f f the power str k o h P o as is ppar n f m a nspsotioh f FIG. 3. However, the piston inertia load again reverses in polarity at the mid-portions of the power stroke of the end 41A. of he iston who ehoon ho oot iood oads again build up toward the peak value, as indicated by the reference character A, notwithstanding that the gas loads progressively diminish in magnitude during the last half of the power stroke.

In accordance with the present invention a pad of pressurized fluid is developed and maintained between the adjacent surfaces of the piston shoes and the swash plate 33. Each pad of pressurized fluid is effective to balance both the gas and inertia loads on the piston shoe and prevents frictional engagement of thepiston shoe with the swash plate during all phases of operation of the barrel engine. With reference to FIG. 1, it is seen that the end 41A of the piston is formed with an axially extending bore 51 in the side adjacent the swash plate 33. A balance piston 52 has one end slidably disposed within the bore 51 in the side adjacent the swash plate 33. A balance piston 52 has one end slidably disposed witihn the bore 51 and thereby defines a fluid-pressurizing chamber 53 within the end 41A of the piston. The end of the balance piston 52 disposed within the bore 51 is preferably of a sleeve-like configuration to facilitate seating of a coiled biasing spring 54 therein. The other end of the balance piston 52 projects toward the swash plate 33 and is formed with a concave recessed surface 56 which is complementary to the hemispherical outer surface of the piston shoe 44. Thus, a socket connection is atforded between the piston shoe 44 and the balance piston 52 whereby the piston shoe 44 is freely rotatable within the recessed end of the balance piston.

Conduit means are provided for supplying fluid from a source to the fluid-pressurizing chamber 53. The conduit means include a passageway 57 formed in the cylinder block 12A, and a spring-biased check valve 58 is mounted within the passageway 57 for permitting only unidirectional fluid flow inwardly therethrough. The inlet conduit means also include an elongated slotted recess 61 formed in the side wall of each piston 41. As illustrated in FIG. 1, the recess 61 communicates with the inlet passageway 57, and defines, with the wall of the cylinder block 12A, an intake chamber 62 for admitting oil or other fluid to the chamber 53. Passageways 63, 64, and 66 connect the inlet recess or chamber 61 with the fluid pressurizing chamber 53. A drain passageway 67 is formed in a side wall of the bore 51 and communicates with the passageway 63 to enable excess fluid to be vented from the fluid-pressurizing chamber 53 to the recess '61 in the course of operation of the balancing piston arrangement to thereby facilitate proper positioning of the balance piston 52 in the end 41A of the main or power piston 41.

Second conduit means are provided for conducting fluid under pressure from the fluid pressurizing chamber 53 through a piston shoe 44 and between adjacent surfaces of the piston shoe and swash plate to provide the pad of pressurized fluid for balancing out the piston shoe loads as described hereinabove. As illustrated in FIG. 1 the balance piston 52 is formed with' a passageway 69 which connects the fluid-pressurizing chamber 53 with the concave recessed surface 56 of the balancing piston. Also, the hemispherical surface of the piston shoe 44 is ground flat, as indicated by the reference numeral 71, and a port 72 extends through the piston shoe. It will be apparent from an inspection of FIG. 1 that the flat surface 71 insures continuous communication of the port 72 with the passageway 69 regardless of the angular position of the piston shoe within the recessed end of the balance piston 52.

In the operation of the load balancing arrangement illustrated in FIG. 1, movement of the balance piston 52 inwardly of the bore 51 during the power stroke of the main power piston 41 is effective to seat the check valve 58 and thereby pressurize the fluid contained within the chamber 53. The pressurized fluid thus obtained in the chamber 53 is conducted through the passageway 69 and port 72 to the interior of the hollow piston shoe 44 and is manifested as a pad of pressurized lubricant effective to maintain the piston shoe 44 in spaced relation to the inclined surface of the swash plate 53.

It will be appreciated that a predetermined magnitude of pressure must be developed within the fluid-pressurized chamber 53 and maintained between the piston shoe 44 and the swash plate if the pad of pressurized fluid is to be effective to completely balance the combined loads on the piston shoe and thereby function in the manner desired. The gas force acting on the exposed surface of the power end 41A of the piston is the force which produces the necessary pressurization of the fluid within the chamber 53. Thus, the'balancing force or pressure on the shoe 44 is'proportional to the load applied to the shoe and is generated by the same force applying the load.

In like manner the end 41B of each piston is formed with an axially extending inner bore 81 in which a balancing piston 82 is mounted for sliding movement and defines a fluid-pressurizing chamber 83. A biasing spring 84 is disposed within the chamber 83 for biasing the piston 82 outwardly of the bore 81. -An inlet passageway 87 is formed in the cylinder block 12A and a check valve 88 is mounted therein. The elongated slot 61 in the side wall of the piston 41 communicates with the inlet passageway 87 and defines a chamber 92 therewith. The chamber 92 is separated from the chamber 62 by an inwardly extending web 93 on the block 12A to afford a separate inlet chamber for the fluid-pressurizing chamber 83. The chamber 92 communicates with the chamber 83 through a series of interconnected passageways 94, 96, and 97. A port 98 is formed in the side wall of the bore 81 and communicates with the passageway 94 for venting excess fluid from the chamber 83. The chamber 83 is connected with the interior of the hollow hemispherical-shaped piston shoe 47 through a passageway 99 formed in the balancing piston 82 and a port 101 formed in the piston shoe 47. The operation of the above-described balancing arrangement for the piston shoe 47 is substantially like that described hereinabove with reference to the piston shoe 44.

With reference now to FIG. 2 there is illustrated another embodiment of a balancing piston mechanism constructed in accordance with the present invention. In the arrangement illustrated in FIG. 2 the barrel engine is indicated generally by the reference numeral 111 and includes a cylinder block 112 which is formed with one or more cylinder bores 113. A main power piston assembly 114 is mounted for reciprocation within the bore 113 and defines an expansible chamber 116 therein. A spark plug -117 is mounted within the cylinder block 112 for igniting a fuel-air mixture supplied to the chamber 116 through a passageway 118 and past a control valve 119.

A swash plate 121 is mounted at a fixed angle of inclination on a shaft 122, and the axis of rotation of the swash plate and shaft is disposed parallel to the direction of reciprocation of the piston 114. The end 123 of the piston 114 which projects outwardly of the bore 113 is formed in a spherical shape, and a piston shoe 124 is mounted thereon in a swivel or ball and socket connection as illustrated in FIG. 2. Thus, movement of the piston 114 outwardly of the bore 113 from the top dead-center position illustrated in FIG. 2, during a power stroke is eflective to rotate the swash plate 121 and shaft 122 in a conventional manner. Continued rotation of the swash plate 121 subsequently returns the piston 144 to the top dead-center position illustrated to complete one cycle of operation.

It will be appreciated that gas and inertia loads are exerted on the piston shoe 124 in the course of reciprocation of the piston 144 in substantially the same manner as pointed out hereinabove with reference to the construction illustrated in FIG. 1, and in the manner indicated in FIG. 3. The arrangement illustrated in 7 2 a so tnakes ro is on fut bal ns g o t e s and iner ia loa s thus ex e on he P s on shoe 1% Th struc ura me s o a com l shi th an in aetion include an axi ll exten in bo 3 forme withi th p s on 1 s l an a di n o 132 of somewhat ar e d am te ha t e or 1 is or in he nner end o ion of he is on in ax l a ntn n with the bo e 1 1 A baia e ns P o s a smelt r diamete en ddd s bl m u in he h 1 1 and a l r r dia et r nd 1 35 iidab m un d n th bin? d?- As il t sti' t d in IG- 2 h d 33. has a surface V134, directly exposed to the gases in the po e c amber ll Mo em t f e ist .3 011ta d y of t e o e 1 2 s lim t d b a flange 6 wh en ages th s surtase ot th Pi on, and mo m n o t e P on ,33 ardl t" the bore 132 is l niite b ab ttnent o e e ect v hou ers al o ed be e the nds 133A nd 1.3-3.3 o the ba ansins P o and h bore 131 and o h main p s Pte y a ventin p ew y 137 s fo m in he mai Pi t 7 fo co ne in he a nul s efined be e n he educed diameter end 13313 and the side walls of the bore 52 w t t e inte i r of a barre e ine 11 to e eby faci ta ree ee r eator m v m nt o the p s 1 within the respective bores 131 and 132. Also, an additional venting passageway 138 may be formed in the piston 144 to interconnect this annulus with the recess e for he P s on n 3 h sid wa s o the h t 1 3; n he i de block 112 are formed with an annular recess 141, and the piston 114. i ormed w t a r pond n an ul cess 142. As illustrated in FIG. 2 the recesses 1'41 and 142 afford an annular Chamber 143, The smaller diamctcr end 133A ot he ba an e P on 3 d fines a fluid-pressurizing chamber 130 within the bore 131, and a P s g ay 4. i t n s the c mb r 14 w h th fluid pressurizing chamber 130. The cylinder block 112 is formed with an inlet pa a o c n uc ing fluid from the source of supply to the fluid-pressurizing chamber 130. A spring-biased ball check valve is disposed Wi hin t e pas a e a 1- o enn ins only unidirectional flow inwardly therethrough.

From the foregoing it will be apparent that conduit means, including the passageways 147 and 146, enable flui to be c v y d ro a source f suppl to the fl id.- Pressuriz ng chamb r 2!)e me o t Pis on 1 3 inw rdly of the bor ,3 y th gase actin n the u face 134 during the power stroke of the piston is effective to pressurize the fluid thus conveyed to chamber 130 while imul aneous y au g t e heek. v lve 1 8 t e s a d in flow bloeking re ati the P a way 147.

Additional conduit means are provided for conducting the fluid thus pressurized from the chamber 130 through the piston shoe 124 an twe n the adjac n sur ac of the sh e 12 nd e swash Plate 1271- These d tional con ui m a n de a p ssage y 151 orme n e P ton. '11-4 a d t m n t n in a re sed su fase l52 in the u erm s nd of t e ba 23- A p ssa eway 153 in erconne t e c amber thu a ed y the s rface 15.2 with a. r ce s L tn d the u der d of the piston shoe 1Z4 facing the swash plate 121. Thus, the recess 154 in the piston shoe is continuously maintained in omm n ca ion w t he fl -press uinin chamber 131) regardless of the angular position of the pi ton shoe on h al end 23- lin tepp d con tru i n o e a anc g p t n 13 n bles a mul ipli ation eff c of th g Pressure to be obtained with respect to the pressure prod ced in the cham er 13!!- T t i ina m ch a h u ac exposed to the g s in the chamb r 1- 6. o lar e area than the inner s rf ce of he en 1 34 a lar er dui p essure is e e ed in. th chamb r 130 th n. Pre rai s n the chamber 116-, T s reas f the p ton 13 be p opor ioned, in rel on to h a a at the piston shoe 124, to achieve optimum balancing for any se eet s e d of op a o the barrel e in i s.-

In accordance with the present invention a novel bal: ancing arrangement is provided for balancing both the gas and inertia loads on a piston shoe in a barrel engine of the general kind described. The balancing action is obtained by a construction which is of a quite simple nat e u neverthe qui effective in ope a i n u thermore the present invention enables optimum balaucing to be achieved for any selected speed of operation of the engine, and the high pressure fluid developed by the balancing arrangements of the present invention can also be utilized to provide lubrication for the main or power piston of the barrel engine.

Hence, while I have illustrated and described the PIC; ferred embodiments of my invention, it is to be under: s o d that these a e ea a e o ar a io a od fication- I claim:

1. In a barrel engine of the kind which includes a P o i ee ble a lin ar di c n nd a s ash plate rotatable about an axis disposed parallel to the direction of reciprocation of the piston wherein a piston shoe is interposed between the piston swash plate and is slidable on the swash plate to convert the line r bas ion of he P t o ry mo ion o the swash plate, means forsupplying a fluid under pressure between the piston shoe and swash plate to balance both the gas and inertia loads of the piston which are exerted on the P ton shoe du i r ciproc t on o he p s on, a d me comp is n a b e te m d n erna ly of t p ston and ex end n x al h e n, a b an pis n d biy m unted within th re a defin n a 'fiuid pressurizing chamber therein, first conduit means for con, i s u d t the u d-Pr sur z n chamb r, al e mean for p eventing v how of flu f om he chame th h e first c nduit tn ans he eby m e n n f the balance Pi ton in ar y o t o e durin s oeati of t e P s s fie t p e u he fluid thin th uid-Pt ssut in mber nd s n conduit means for conducting fluid under pressure from said chamber through the piston shoe and between the a ja en s r ce o h s on oe n s s a e- .2- n a barrel e o the k nd h h i c ud a piston reciprocable in a cylinder block and a swash plate rotatable about an axis disposed parallel to the direction of reciprocation of the piston and wherein a piston shoe is interposed between the piston and swash plate and is slidable on the swash plate to convert the linear motion of the piston to rotary motion of the swash plate, means for supplying a fluid under pressure between the piston shoe and swash plate to balance both the gas and inertia loads of the piston which are exerted on the piston shoe during reciprocation of the piston, said means compris ing a bore formed internally of the piston and extending axially therein, a balance piston having a first end por tion slidably mounted within the bore and defining a fluid: pressurizing chamber therein, said balance piston having a second end portion projecting toward the swash plate and formed with a surface shaped complementary to the exterior configuration of the piston shoe and afiording a socket connection therewith, first conduit means for convey'ing fluid to the fiuid-pressurizing chamber, valve means for preventing reverse'flow of fluid from the chamber through the first conduit means, whereby movement of the balance piston inwardly of the bore during reciprocation of the piston is effective to pressurize the fluid within the fluid-pressurizing chamber, and second conduit means for conducting fluid under pressure from said chamber through the piston shoe and between the adjacent surfaces of the piston shoe and swash plate.

I a barr l e gin oi he k nd whic i clu a pist eiproe le in cylin er block. and a ash Pla ota a le. abo an s di pos d parallel o h dir ction of. re pro ation o e pis on nd wherein a piston shoe. is n erposed between the P t n d swash plate and is slidable on the swash plate to convert the linear motion of the piston to rotary motion of the swash plate, said piston shoe having a spherical configuration in the part adjacent the piston, means for supplying a fluid under pressure between the piston shoe and swash plate to balance both the gas and inertia loads of the piston which are exerted on the piston shoe dUIlIig reciprocation of the piston, said means comprising a bore formed internally of the piston and extending axially therein, a balance piston having a first end portion slidably mounted within the bore and defining a fluid-pressurizing chamber therein, said balance piston having a second end portion projecting toward the swash plate and formed with a surface shaped complementary to the spherical surface of said piston shoe to afiord a socket connection therewith, spring means normally biasing said balance piston outwardly of the fluid-pressurizing chamber to thereby bias the piston shoe toward engagement with an adjacent surface of the swash plate, first conduit means for conveying fluid to the fluid-pressurizing chamber, valve means for preventing reverse flow of fluid from the chamber through the first conduit means, whereby movement of the balance piston inwardly of the bore during reciprocation of the piston is effective to pressurize the fluid within the fluid-pressurizing chamber, and second conduit means for conducting fluid under pressure from said chamber through the second end portion of the balance piston to lubricate the socket connection and through the piston shoe to afford a pad of lubricant between the adjacent surfaces of the piston shoe and swash plate.

4. In a barrel engine of the kind which includes a power piston reciprocable in a bore in a cylinder block and a swash plate rotatable about an axis disposed parallel to the direction of reciprocation of the power piston and wherein a piston shoe is interposed between the power piston and swash plate and is slidable on the swash plate to convert the linear motion of the power piston to rotary motion of the swash plate, means for supplying a fluid under pressure between the piston shoe and swash plate to balance both the gas and inertia loads of the power piston which are exerted on the piston shoe during reciprocation of the piston, said means comprising a bore formed internally of the power piston and extending axially therein, a balance piston having a first end portion slidably mounted within the bore in the power piston and defining a fluid-pressurizing chamber therein, said balance piston having a second end portion which projects away from the swash plate and which includes a surface directly exposed to the variable volume chamber defined by the power piston within the bore of the cylinder block, first conduit means for conveying fluid to the fluid-pressurizing chamber, valve means for preventing reverse flow of fluid from the chamber through the first conduit means, whereby movement of the balance piston inwardly of the bore during a power stroke of the power piston is etfective to pressurize the fluid within the fiuid-pressurizing chamber, and second conduit means for conducting fluid under pressure from said chamber through the piston shoe and between the adjacent surfaces of the piston shoe and swash plate.

5. A barrel engine as defined in claim 4 wherein the balance piston is a stepped piston in which the first end portion is smaller in diameter than the second end portion for generating a larger pressure in said fluid-pressurizing chamber than prevails in the bore of the cylinder block.

6. In a barrel engine of the kind which includes a piston reciprocable in a cylinder block and a swash plate rotatable about an axis disposed parallel to the direction of reciprocation of the piston and wherein a piston shoe is interposed between the piston and swash plate and is slidable on the swash plate to convert the linear motion of the piston to rotary motion of the swash plate, means for supplying a fluid under pressure between the piston shoe and swash plate to balance both the gas and inertia loads of the piston which are exerted on the piston shoe during reciprocation of the piston, said means comprising a bore formed internally of the piston and extending axially therein, a balance piston having an end portion slidably mounted within the bore and defining a fluidpressurizing chamber therein, first conduit means for conveying fluid to the fluid-pressurizing chamber, said first conduit means including a passageway formed in a wall of the cylinder block, valve means disposed in said passageway for preventing reverse flow of fluid from the chamber through the first conduit means, whereby movement of the balance piston inwardly of the bore during reciprocation of the piston is effective to pressurize the fluid within the fluid-pressurizing chamber, and second conduit means for conducting fluid under pressure from said chamber through the piston shoe and between the adjacent surfaces of the piston shoe and swash plate.

7. In a barrel engine of the kind which includes a plurality of power pistons reciprocable in parallel cylinders formed in a cylinder block, a swash plate rotatable about an axis extending parallel to the cylinders, and a piston shoe interposed between each power piston and the swash plate, and wherein each piston shoe is slidable on the swash plate to convert the linear motion of the power pistons to rotary motion of the swash plate, means for supplying a fluid under pressure between each piston shoe and swash plate to balance both the gas and inertia loads of the power piston which are exerted on the piston shoe during reciprocation of the piston, said means comprising a bore formed internal-1y of each power piston and extending axially therein, a balance piston slidably mounted within each bore and defining a fluid-pressurizing chamber therein, first conduit means for conveying fluid to each of said fluid-pressun'zing chambers, valve means for preventing reverse flow of fluid from the chambers through the first conduit means, whereby movement of each balance piston inwardly of its bore during reciprocation of the associated power piston is effective to pressurize the fluid within each of the fluidpressurizing chambers in proportion to the applied load on the power piston, and second conduit means for conducting fluid under pressure from each chamber through an associated piston shoe and between the adjacent surfaces of the piston shoe and swash plate.

8. A barrel engine as defined in claim 7 including vent passageways formed in each of the power pistons for venting excess fluid from the fluid-pressurizing chambers so that the power pistons are always positioned within controllable limits with respect to the swash plate.

9. A barrel engine as defined in claim 7 in which each piston shoe is axially aligned with its associated balance piston and is mechanically connected thereto by a swivel joint eflective to incorporate the shoe in a reciprocable assembly comprising the shoe, the balance piston, and the power piston.

No references cited. 

